1. Field of the Invention
This invention relates to a motor-driven camera which is arranged to drive a plurality of mechanisms by using one and the same motor.
2. Description of the Related Art
Many patent applications have recently been filed for cameras of the kind using the output of one and the same motor for photographing preparatory actions such as a shutter charging action, etc. as well as a film transport for each one frame photographing. For example, U.S. Pat. No. 4,693,578 relates to a camera of this kind. Generally, the camera of this kind is arranged to carry out the photographing preparatory action while the film is being driven and transported (for film winding or rewinding) on the basis of the unidirectional rotation of the motor. Therefore, the camera is required to keep the phases of two driving systems in equivalent states. To meet this requirement, the film transporting action must be performed by driving a sprocket while a film take-up shaft is friction-coupled and rotated at a sufficiently higher speed than the sprocket. This results in a complex structural arrangement. Further, the use of the sprocket alone does not permit detection of a failure in automatic film loading. Besides, slipping which takes place at the friction coupling part has presented a problem in terms of an energy loss.
Among cameras of the kind adopting a method called a prewind system, a camera disclosed in Japanese Laid-Open Patent Application No. SHO 57-89732 also has the above-stated structural arrangement.
To solve the problems stated in the foregoing, the film transport driving system and the photographing preparatory action driving system must be arranged to be independent of each other. For example, these two driving systems may be arranged to be driven by different motors. This method enables the film transporting action to be carried out by directly driving the take-up shaft which has its take-up rotation angle vary with the diameter of a film coil being formed on the take-up shaft. This method is, however, not desirable in terms of cost and space. Meanwhile, there has been proposed a method of driving both a film wind driving system and a shutter charge driving system with a single motor by switching the motor rotation between its normal rotation and reverse rotation, as disclosed in U.S. Pat. No. 4,350,421. However, that method results not only in a complex structural arrangement but also in a large energy loss.
Further, motor driven cameras of the type using a motor as drive source for a film transport, a shutter charge and swinging a movable mirror have recently been proposed in varied kinds. For example, in the cases of cameras disclosed in U.S. Pat. Nos. 4,466,719 and 4,572,636, film winding and rewinding actions are arranged to be both accomplished by using one and the same motor disposed within the camera in combination with a clutch change-over device. Meanwhile, U.S. Pat. No. 4,579,435 discloses a camera which is arranged to enhance the speed and efficiency of the film transporting action by separately using two motors for film winding and film rewinding purposes.
Further, U.S. Pat. No. 4,616,913 has disclosed a camera which is arranged to increase the speed and efficiency of a film transporting speed as much as possible by using different motors, respectively, for film winding, film rewinding and shutter charging.